Recently, an electric vehicle (i.e., EV) and a hybrid vehicle (i.e., HV) have a structure for generating a small noise. Thus, it is difficult for a pedestrian to find these vehicles approaching the pedestrian. In order to increase a recognition degree of the vehicle disposed near and around the pedestrian or the like, the vehicle approach alert device for generating pseudo driving sound is mounted on these vehicles (see, for example, Patent Literature 1). In the vehicle approach alert device, a method for outputting sound is a method for outputting the sound by setting a coded data, which is prepared by converting and coding the output sound data such as PCM data (i.e., pulse code modulation data) stored in a memory of a microcomputer, i.e., converting and coding the magnitude of the sound to a data code, into a D/A converter and a PWM output device. Further, in the vehicle approach alert device, an output of the pseudo driving sound is performed when a road noise is small and the vehicle speed is low. When the vehicle is in an acceleration state, the vehicle approaches rapidly, and therefore, the risk for the pedestrian increases. Thus, the musical pitch (i.e., output sound pitch) is increased according to the increase of the vehicle speed, or the sound pressure is changed according to the acceleration operation condition of a driver, so that the effect of “fluctuation” of sound is added. Thus, the pedestrian easily find the approach of the vehicle, and further, the pedestrian can suppose the driving condition of the vehicle.
When the sound pressure is controlled according to the acceleration opening degree in order to imagine the acceleration state of the vehicle, the sound pressure may increase rapidly if the driver operates to press an acceleration pedal drastically. Accordingly, the pedestrian may be surprised more than necessary, and/or the ambient noise may increase, so that antinomy occurs.